> What is the highly flammable and explosive gas given off by the batteries used in battery-operated ignition systems and

What is the highly flammable and explosive gas given off by the batteries used in battery-operated ignition systems and

Posted at: 2015-01-07 
Hydrogen. Oxygen is also produced. It is not explosive or flammable, but it helps the hydrogen burn/explode when ignited.

The question sounds like something from a science test, are you taking a test or doing homework and want us to give you the answers?

Your question is somewhat unclear, but hydrogen is probably the answer.

hydrogen